During his presidency, Lyndon Johnson notoriously said of an international ally that he was a “sonofabitch, but he’s our sonofabitch.”

LBJ, no sentimentalist or stylist, nonetheless often had a way with words.

His public attitude might also be ascribed, from time to time, to leaders on both the left and the right when they’re confronted with some of their more radical supporters — even if, in private, they can only shake their heads.

Presumably responsible Democratic and liberal leaders found themselves sometimes embarrassed by Code Pink and other protesters who resorted to violence and goofy street-theater tactics to bring attention to their varied causes, the most recent being the war in Iraq. MoveOn.org depicted George W. Bush as Hitler in a 2004 commercial, and Bush was regularly mocked and burned in effigy as a war criminal by elements of the angry left. Cindy Sheehan made herself emblematic of the embarrassing left.

Democratic leaders in the late 1960s, while sympathetic to the message of the anti-Vietnam War protesters, often found themselves attempting to keep activists at arm’s length while working toward their goal of getting the U.S. out of Southeast Asia. Republicans of the era — claiming to speak for a “silent majority” — did their utmost to drape the more radical elements of the anti-war movement around the necks of Democratic Sens. Hubert Humphrey of Minnesota and Ed Muskie of Maine, among others. In the end, however, the protesters might have prolonged the war, as Middle America resisted being on the same side as a scruffy bunch of spoiled brats.

Today, conservatives and GOP leaders are finding turnabout is, indeed, fair play: Right-wing protesters carrying guns or signs of President Barack Obama sporting a Hitler mustache — or ridiculously claiming he wasn’t born in the United States — are finding their political adversaries (including the gentle and soft-spoken folks at MSNBC) doing their level best to indict all those on the right for the actions of a lesser number.

Yet what the elites don’t understand is that by mocking the opposition from on high, it does not humiliate or embarrass it; it makes it even angrier, stronger and more resolute.

Welcome to the big asylum — 2009 — where everybody has a blog and the attention is on the more radical elements of the right.

From the end of the Civil War up until the beginning of the 20th century, the GOP raised the notorious “bloody shirt” of that conflagration to remind voters it was the Democrats who were the party of the South and of slavery. It was an effective technique by Republicans to hold onto the White House during most of the era.

Taking a step back, cooler heads know that radicalism has a long tradition in America, from the Shays’ Rebellion to the Whiskey Rebellion to John Brown’s attempt to start an insurrection among the slaves of Virginia — not to mention the many pro-slave whites he and his sons killed in Kansas. Carrie Nation often resorted to violence in her attempt to turn America into a country of teetotalers. Unfortunately, she succeeded for a time, until Franklin D. Roosevelt had the sober sense to know that a man without a job could sometimes use a good stiff drink.

During Janet Reno’s tenure as attorney general — when dozens of innocent people were killed after she ordered the Bureau of Alcohol, Tobacco and Firearms and the FBI to storm the barricades of the Branch Davidian compound — she gave the excuse that they were religious nuts with guns, to which satirist P.J. O’Rourke retorted, “This nation was founded by religious nuts with guns!”

The problem is there are nuts, and then there are nuts. Since the beginning of the republic, there have been zealots in the cause of righteousness such as Sam Adams and Thomas Paine, always pushing, always agitating. In the cause of emancipation, suffrage, war, peace, coinage, land and the expansion of freedoms, this country has always allowed and then finally acceded to the demands of the radical visionaries. The status quo has rarely been acceptable for Americans, and principled nuts have served a valuable purpose.

The zealots of the extreme right and extreme left today have fewer claims on such noble aspirations, and many of their antics seem more about adding to their YouTube profiles, being covered by the media or driving up their ratings than about achieving real goals. Ignorance and hate seem to be their organizing principles. Having recently been the target of a left-wing disinformation campaign, we know about the sting of an info-battle, especially the now-commonplace death threat, brought about by rants.

It isn’t enough to say it comes with the turf. I’ve been at this game for nearly 40 years, and in all that time, no one has ever told me my days on the streets were numbered — until now. Adlai Stevenson once said his “definition of a free society is a society where it is safe to be unpopular.”

Boat rockers come in two different forms: those who rock the boat to change course and those who rock the boat simply to scare other people.

Two things are missing from both sides today: decency and expanded knowledge. Indeed, both extremes seem to revel in anti-intellectualism and bad manners. Street theater and attention-getting antics are all well and good, but they must serve a purpose. Once a cause has the crowd’s attention, it must do something beyond simply causing more acting up.

Many believed the anti-Iraq war protesters had a legitimate point. And many today believe the fear on the right of Big Obama and his notions to “remake America” is also legitimate, but in both instances, the messages were muddled because of the more extreme elements.

Many conservatives find the birthers especially frustrating, as it isn’t necessary to make up things about Obama. The truth of his policies is scary enough, and if the shock troops of the right want to be the conservatives’ sonofabitches, they’d better learn more effective and practical ways to protest the liberal policies of Obama than simply painting mustaches on photographs. They need to recall the words of the great philosopher Emil Faber, founder of Faber College: “Knowledge is good.”

Craig Shirley is the president of Shirley & Banister Public Affairs and is the author of the forthcoming “Rendezvous With Destiny: Ronald Reagan and the Campaign That Changed America.”